Function: indent-code-rigidly

Indent all lines of code, starting in the region, sideways by ARG columns.
Does not affect lines starting inside comments or strings, assuming that
the start of the region is not inside them.

Called from a program, takes args START, END, COLUMNS and NOCHANGE-REGEXP.
The last is a regexp which, if matched at the beginning of a line,
means don't indent that line.